Blank for a carton box having corner locking

ABSTRACT

The panels meeting at the respective corner of a carton box are locked by means of a locking tongue of one panel being inserted into a locking slit in the other panel, said locking tongue having a hook-like projection at its upper edge which can be inserted into the slit merely by first flexibly bending the tongue so that the hook-like projection may engage the end of the slit.

"United States Patent [191 Persson [4 1 Sept. 2, 1975 BLANK FOR A CARTONBOX HAVING CORNER LOCKING [75] Inventor: Karl Rune Persson, Halmstad,

Sweden [73] Assig'nee: Sprinter Pack AB, Halmstad,

Sweden [22] Filed: Apr. 23, 1974 [21] Appl. No.: 463,410

[30] Foreign Application Priority Data May 9, 1973 Sweden 065294 [52]US. Cl 229/35; 229/75 [51] Int. Cl. B65D 5/26 [58] Field of Search229/31 R, 31 F8, 33, 35

[56] References Cited UNITED STATES PATENTS 2,718,998 9/1955 Bemiss229/35 2,955,737 10/1960 Armeson 229/35 2,982,464 5/1961 Wingate 229/353,393,859 7/1968 Glummo... 229/35 3,608,811 9/1971 Frick 229/31 RPrimary ExaminerDavis T. Moorhead Attorney, Agent, or FirmOstro1enk,Faber, Gerb & Soffen ABSTRACT The panels meeting at the respectivecorner of a carton box are locked by means of a locking tongue of onepanel being inserted into a locking slit in the other panel, saidlocking tongue having a hook-like projection at its upper edge which canbe inserted into the slit merely by first flexibly bending the tongue sothat the hook-like projection may engage the end of the I slit.

3 Claims, 6 Drawing Figures PATENTED 2 SHEET 1 OF 2 FIG.1

BLANK FOR A CARTON BOX HAVING CORNER LOCKING The present inventionrelates to a blank for carton boxes having corner locking of the kindset forth in the preamble to the accompanying main claim.

A number of such corner locks are known. The object of the invention isto effect a new design of such a corner lock, where the locking tongueof the one side wall panel, upon erecting the blank, guidingly movesinto a locking slit in the other side wall panel end flap and snaps to asecure locking position when the end edges associated with therespective corners of the side wall panels lie adjacent each other. Thisis made possible by a blank having the distinguishing features set forthin the accompanying claims.

A suitable embodiment of the blank, and the erected carton box havingcorner locking according to the invention will now be described, makingreference to the attached drawings.

FIG. 1 shows a carton box blank having corner locking according to theinvention,

FIG. 1a is an enlarged partial view of the blank,

FIG. 1b corresponds to FIG. la and shows'a somewhat modified embodiment,

FIG. 2 is an enlarged diagrammatic perspective view of a corner portionof the box, where the one side is erected and has its end flap foldedinwards for receiving the locking tongue of the other side, the tonguebeing shown in an erected position, with the associated side wall in alying position,

FIG. 3 shows the same position as FIG. 2 in a view from the side, thelocking tongue and its side wall being shown with dotted lines in anumber of positions during the introduction of the locking tongue intothe locking slit,

and FIG. 4 is a diagrammatic perspective view seen towards the inside ofa corner with the locking tongue in the locked position.

The blank in FIG. 1 has a bottom and sidewalls 11,12, 13,14 hingeablyattached thereto by means of hinged folding lines, and a lid 15. For thesake of simplicity, only the corner portion of the blank for side walls11,12 will be described, since remaining corner portions are identicalwith it. The lid may possibly be excluded, the blank then being intendedto form a tray.

Side wall 11 may be folded up along a hinged folding line 16, and sidewall 12 may be folded up along a hinged folding line 17.

Side wall 11* has an end flap 18 which can be folded in along a partedhinged folding line 19,1911, and side wall 12 has an end flap in theshape of a tongue 20 which can be folded in along a hinged folding line21.

In the end flap 18 there is a locking slit consisting of a straightouter slit portion 22, parallel with the hinged folding line butsomewhat displaced sideways. The outer end 23 of the slit portion isdirected towards the outer hinged folding line 19a and extends up to itto bound a small our 25, and a slantingly directed slit portion 26 whichextends in a direction towards side wall 12 in FIG. 1. The inner end ofthe straight slit 22 connects with the outer end portion 24 of theslanting slit portion. Between hinged folding line 19 and the slantingslit portion 26 a wedge-shaped portion 27 is thus obtained, the narrowend of which is terminated by the end edge obtained at the end portion24 of slit 26.

The tongue 20 of side wall 12 has its hinged folding line 21 situatedsomewhat to one side of the end edge 28 of the side wall. Both the sideedges 29,30 of the tongue extend arcuately outwards and meet at theouter end of the tongue. At its inner edge, the inner side edge 29connects with the slit 28a which, in the embodiment according to FIG.1a, separates the end flap 18 from the wall 12 to make end edge 28. Theslit 28a extends up to the hinged folding line 21, where the slit has asmall end portion 31 directed towards hinged folding line 21. This endportion 31 is at a distance from hinged folding line 17 which issubstantially the same as the distance between hinged folding line 16and end portion 24 of the slanting slit portion which is slantinglydirected towards hinged folding line 19.

Through the shaping of tongue 20 described above, it will have a freelyprojecting flexible corner flap 32 lying in the vicinity of end edge 28of the side wall. The corresponding edge of tongue 20 forms a lockingedge 32a (FIGS. 2, 3, 4) which is parallel with the hinged folding line21, but is displaced sideways a distance which is approximately the sameas double the carton thickness of the blank in question. The tongue ishereby given a neck 20a which has a corresponding short length.

In the embodiment according to FIG. lb, the end flap 18a is hingeablyconnected at its lower edge to side wall 12 along a hinged folding line28b. To guide the necessary double folding of flap 18a there is a 45fold line 34. A tighter corner in the tray is obtained by this process.In all other respects, both the blanks in FIG. 1a and 1b are the same.

In FIGS. 2, 3 and 4, only the erection of the blank according to FIG. 1ais shown, but erecting the blank according to FIG. 1b takes place in thesame way.

As may be seen from FIG. La (and FIG. 111 also) the outer or upper edge30 of the tongue 20 is connected via a shoulder 35 to the outer or upperend of the hinged folding line. The edge of the shoulder is terminatedby an end portion 30a at the bottom of the wedge-shaped space or gapbetween the end edge 12a of the side wall l2 and the opposite portion ofedge 30.

To obtain the locking as intended by the invention, the distance fromcorner point 36 (FIG. 1a) at the abutting ends of hinge folding lines16,17 to the outer or upper end 23 of slit portion 22 should beapproximately the same as, suitably slightly less than, the distancefrom point 36 to the outer or upper end of folding line 21 and the endportion 30a of edge 30 respectively.

The distance from point 36 to the outer or upper end 26 of the slantingslit portion is further approximately the same as, suitably slightlyless than, the distance from point 36 to the inner or under end offolding line 21 and the end portion 31 respectively. The intention inthe selection of these distances will be seen below.

When erecting the blank in the machine, the parts of the blank will notnormally assume the position shown in FIG. 2, there usually being, amainly simultaneous erection of the side walls and folding in of the endflaps. The positionaccording to FIG. 2 is therefore only intended tofacilitate understanding the invention.

When erecting side walls 11 and 12, the end flap 18 is folded in beforethe tongue .20.

The side wall 1 1 is folded up by bending along folding line 16.

Side wall 12 is however folded up by a new method, namely by partlyfolding along folding line 17 and by partly simultaneous bending wall12, as is shown by the different positions in FIG. 3, so that the tonguewill lie at a minor distance from folding line 17 and the upper end 30bof the tongue will be moved in to a path of movement 37, the radius ofwhich to folding line 17 is approximately equal to, suitably somewhatsmaller than, the distance between the upper end 23 of slit 22 andfolding line 17. By bending wall 12 in this way, the tongue 20 can passin through slit 22,26 so that the shoulders 35 of the tongue engageabout the upper end 23 (FIGS. 3 and 4) of slit 22 in a hook-like manner.A

very secure lock is hereby obtained. This is secured by I the lowercorner flap 32 of the tongue being also bent sideways when it passesthrough the slanting slit portion 26, to spring back again afterwards tothe locking position shown in FIG. 4, where the tongue edge 32a abutsthe wedge-shaped portion 27 of end flap 18. This lower locking preventswall 12 from bending back again, which could cause shoulder 35 torelease its aforementioned grip.

To facilitate bending of side wall 12 the grain of the carton materialis longitudinal in the side wall.

The blank according to the invention gives smooth outside side walls,which is an advantage, amongst other things when decoration is to beapplied to the side walls. There are furthermore no slits in the sidewalls which could reduce the tightness of the tray or box. Moreover, thecorners will be stable because of the special arrangement of tongue 20and end flap 18 according to FIG. 4.

What I claim is:

l. A blank for a carton box or tray having side walls extended at theirends with end flaps foldable along hinged folding lines provided at therespective corner of the box, a locking slit being provided at thehinged folding line of a first one of the end flaps, a second slitdiagonally aligned with the locking slit and being joined to the lockingslit at the lower end of the locking slit, the second end flap forming atongue having a tapered free end, a widened central portion and a narrowneck portion in the region where it is joined to its side wall alongsaid hinged folding line, characterized in that the inner end of thetongue is separated from its side wall by a third slit, that theopposite side of the locking tongue extends from the outer end of thehinged folding line of the tongue and forms a wedge-shaped space or gapwith the edge of the adjacent side wall, that in the vicinity of itsinner end said gap has a width which is preferably approximately doublethe thickness of the blank, that one side of the gap forms the edge of ashoulder-shaped portion, and that the distance from the corner point ofthe blank, lying at the merging ends of the hinged folding lines of theside walls, to the outer end of the locking slit is approximately thesame as the distance from said corner point to the bottom of saidwedge-shaped gap, so that the inner end of the tongue opposite the gapenters into and is bent by the second slit upon an insertion of thetongue into the locking slit and that the shoulder-like portion of thetongue is hooked into the slit to a locking position upon erecting theblank, with the inner end of the tongue being passed through the secondslit and locked by the portion of the end of the first end flap betweenthe first end flap folding line and the second slit.

2. Blank according to claim 5, characterized in that the grain directionof the carton material is longitudinal in the side wall, provided with atongue, to facilitate bending of the side wall.

3. A blank for a carton box or tray having side walls extended at theirends with end flaps foldable along hinged folding lines at therespective corner of the box, a locking slit being provided at thehinged folding line of the one end flap, and the other end flap forminga locking tongue which is insertable into the locking slit and lockablein it, characterized in that one side of the locking tongue starts fromthe outer end of the hinged folding line of the tongue, and forms awedge-shaped space or gap with adjacent side wall, that in the vicinityof its inner end the gap has a width which is preferably approximatelydouble the thickness of the blank, that one side of the gap forms theedge of a shoulder-shaped portion, and that the distance from the cornerpoint, lying at the ends of the hinged folding lines of the side walls,to the outer end of the slit is approximately the same as the distancefrom said corner point to the bottom of said wedge-shaped gap, so thatthe side wall of the tongue must be bent in order that the shoulder-likeportion of the tongue can be hooked into the slit to a locking positionon erecting the blank; said tongue being provided with a short neck, theinner end of which is hingeable along the hinged folding line of thetongue, and the length of which is preferably approximately the same asdouble the thickness of the blank, that the inner side edge of the neckmerges into a locking edge parallel with the hinged folding line, saidlocking edge line connecting with the inner end of the adjacent sideedge of the tongue so that the corner portion of the tongue between thelocking edge and the inner side edge of the tongue forms a free flexiblecorner flap, that the locking slit in the other end flap lies between anouter and an inner portion of the hinged folding line for this end flap,and is composed of an outer straight slit portion and an innerslantingly directed slit portion, that the outer slit portion isparallel with the end flap hinged folding line, but is placed sidewaysrelative to it, that the outer end of the straight slit portion connectswith the outer portion of the hinged folding line of the end flap via aslit end portion, that the slanting slit portion is taken up in the endflap and forms an acute angle with the inner portion of the hingedfolding line and has an end portion at its outer end which extends intowards the inner portion of the end flap hinged folding line, that theinner end of the straight slit portion connects with said end portion,and that the distance from the transition between the straight slitportion and the slanting slit portion to adjacent hinged folding linebetween the side wall and the box bottom is substantially the same asthe distance between the inner end of the hinged folding line of thetongue and the hinged folding line between the associated side wall andthe box bottom, so that on erecting the box and inthe tongue, to alocking position.

=l l l

1. A blank for a carton box or tray having side walls extended at theirends with end flaps foldable along hinged folding lines provided at therespective corner of the box, a locking slit being provided at thehinged folding line of a first one of the end flaps, a second slitdiagonally aligned with the locking slit and being joined to the lockingslit at the lower end of the locking slit, the second end flap forming atongue having a tapered free end, a widened central portion and a narrowneck portion in the region where it is joined to its side wall alongsaid hinged folding line, characterized in that the inner end of thetongue is separated from its side wall by a third slit, that theopposite side of the locking tongue extends from the outer end of thehinged folding line of the tongue and forms a wedgeshaped space or gapwith the edge of the adjacent side wall, that in the vicinity of itsinner end said gap has a width which is preferably approximately doublethe thickness of the blank, that one side of the gap forms the edge of ashoulder-shaped portion, and that the distance from the corner point ofthe blank, lying at the merging ends of the hinged folding lines of theside walls, to the outer end of the locking slit is approximately thesame as the distance from said corner point to the bottom of saidwedge-shaped gap, so that the inner end of the tongue opposite the gapenters into and is bent by the second slit upon an insertion of thetongue into the locking slit and that the shoulder-like portion of thetongue is hooked into the slit to a locking position upon erecting theblank, with the inner end of the tongue being passed through the secondslit and locked by the portion of the end of the first end flap betweenthe first end flap folding line and the second slit.
 2. Blank accordingto claim 5, characterized in that the grain direction of the cartonmaterial is longitudinal in the side wall, provided with a tongue, tofacilitate bending of the side wall.
 3. A blank for a carton box or trayhaving side walls extended at their ends with end flaps foldable alonghinged folding lines at the respective corner of the box, a locking slitbeing provided at the hinged folding line of the one end flap, and theother end flap forming a locking tongue which is insertable into thelocking slit and lockable in it, characterized in that one side of thelocking tongue starts from the outer end of the hinged folding line ofthe tongue, and forms a wedge-shaped space or gap with adjacent sidewall, that in the vicinity of its inner end the gAp has a width which ispreferably approximately double the thickness of the blank, that oneside of the gap forms the edge of a shoulder-shaped portion, and thatthe distance from the corner point, lying at the ends of the hingedfolding lines of the side walls, to the outer end of the slit isapproximately the same as the distance from said corner point to thebottom of said wedge-shaped gap, so that the side wall of the tonguemust be bent in order that the shoulder-like portion of the tongue canbe hooked into the slit to a locking position on erecting the blank;said tongue being provided with a short neck, the inner end of which ishingeable along the hinged folding line of the tongue, and the length ofwhich is preferably approximately the same as double the thickness ofthe blank, that the inner side edge of the neck merges into a lockingedge parallel with the hinged folding line, said locking edge lineconnecting with the inner end of the adjacent side edge of the tongue sothat the corner portion of the tongue between the locking edge and theinner side edge of the tongue forms a free flexible corner flap, thatthe locking slit in the other end flap lies between an outer and aninner portion of the hinged folding line for this end flap, and iscomposed of an outer straight slit portion and an inner slantinglydirected slit portion, that the outer slit portion is parallel with theend flap hinged folding line, but is placed sideways relative to it,that the outer end of the straight slit portion connects with the outerportion of the hinged folding line of the end flap via a slit endportion, that the slanting slit portion is taken up in the end flap andforms an acute angle with the inner portion of the hinged folding lineand has an end portion at its outer end which extends in towards theinner portion of the end flap hinged folding line, that the inner end ofthe straight slit portion connects with said end portion, and that thedistance from the transition between the straight slit portion and theslanting slit portion to adjacent hinged folding line between the sidewall and the box bottom is substantially the same as the distancebetween the inner end of the hinged folding line of the tongue and thehinged folding line between the associated side wall and the box bottom,so that on erecting the box and inserting the locking tongue in thelocking slit the flexible corner flap of the tongue will pass throughthe slanting slit portion while the corner flap is bent sideways, saidflap snapping back in again, and over the end portion of adjacentportion in the totally inserted position of the tongue, to a lockingposition.